We have discovered the forces which are sufficient and necessary to produce the keyhole shape of the newt neural plate from a hemispheric sheet of cells one cell thick. We find that the joint operation of two forces effects this transformation: 1) a regionally programmed shrinkage of the neural plate (accomplished by contraction of the apical surfaces of the neural plate cells and elongation of the cells perpendicular to the plate); and (2) displacement of neural plate cells by elongation of the attached underlying notochord. We have also (1) found that the lines of shear correlate with major developmental boundaries; (2) done a spatial and temporal analysis of unresolved tissue tensions in the ectoderm (which do not affect shaping of the neural plate); and (3) constructed a new fate map of the earliest neural plate. Since each cell in the neural plate contributes to the motion of the whole sheet, we used a computer simulation and mathematical analysis ('morphodynamics') to deduce the morphogenesis of the neural plate from the behavior of its component cells. The act of creating the computer simulation was not an end in itself, but rather sharpened our quantitative observation of and experiments on the embryo.